Our Rotary Twin Lobe Compressor / Roots Blower is a positive displacement and constant volume machine that works effectively against variable pressure. Two â8â shaped impellers are mounted on parallel shafts, revolve in opposite direction, and with every revolution a definite volume of air is trapped & carried across the housing to the compressor outlet, where the air is discharged. With continual speed operation, the displaced amount is basically the same at a constant pressure, barometric pressure or temperature. With the increasing speed of the compressor against a constant pressure, the volume of air delivery is also increases. The helical timing gears control the relational position of the impellers and maintain a definite clearances. This ensures operation without the lubrication requirement inside the air casing.